LED pumped polymer laser sensor for explosives

The authors would like to acknowledge financial support for this research from the EPSRC HYPIX project (grant number EP/ F059922/1 and EP/F05999X/1), and the TIRAMISU project, funded by the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 284747.A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light-emitting diode. The laser shows a two-stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The 'double-threshold' phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface-emitted output under optimized LED excitation. A very compact explosive vapor sensor is demonstrated based on a distributed feedback polymer laser pumped by a commercial InGaN light-emitting diode. The laser shows a two-stage turn on of the laser emission, for pulsed drive currents above 15.7 A. The 'double-threshold' phenomenon is attributed to the slow rise of the ∼30 ns duration LED pump pulses. The laser emits a 533 nm pulsed output beam of ∼10 ns duration perpendicular to the polymer film. When exposed to nitroaromatic model explosive vapors at ∼8 ppb concentration, the laser shows a 46% change in the surface-emitted output under optimized LED excitation.Publisher PDFPeer reviewe

Optimal Pipeline Design with Increasing CO2 Flow Rates

AbstractWide deployment of carbon capture and storage (CCS) will require extensive transportation infrastructure, quite often in the form of pipelines. The rollout of such large-scale infrastructure would undoubtedly require very large investments. In regions with several CO2 emission sources, it is possible that not all of the major CO2 sources will implement CCS at the same time. Shared oversized pipeline designs are often proposed in order to form a “cluster” of CO2 sources and serve as the backbone for an expanding CO2 transportation infrastructure, to which emission sources will be connected. This paper analyses the economics of using oversized and parallel pipelines for different typical pipeline length and CO2 flow rate combinations. For new CCS projects, the expansion methodology presented in this paper can identify the optimal pipeline design that minimises the cost per tonne of CO2 avoided over the life of the project. For existing projects, the expansion methodology identifies the optimal pipeline design change, which may include either using an existing pipeline as CO2 supply increases or duplicating pipelines

Gravitational Collapse of Phantom Fluid in (2+1)-Dimensions

This investigation is devoted to the solutions of Einstein's field equations for a circularly symmetric anisotropic fluid, with kinematic self-similarity of the first kind, in $(2+1)$-dimensional spacetimes. In the case where the radial pressure vanishes, we show that there exists a solution of the equations that represents the gravitational collapse of an anisotropic fluid, and this collapse will eventually form a black hole, even when it is constituted by the phantom energy.Comment: 10 page

Safety in maritime oil sector: Content analysis of machinery space fire hazards

An in-depth study of the practice within the maritime oil industry was undertaken to ascertain safety issues in seafaring vessels. It was more concentrated on the type of accidents that occur in machine spaces of seafaring vessels in this industry. The main focus of the research was streamlined to fire in machinery spaces. The literature review later concentrated on two of such incidences, they are oil spill and fire events. An investigation was done to assess those factors which actually contribute or are in association to fire outbreak. A content analysis methodology was used to investigate the associative relationships to fire outbreak with the aid of NVivo 9.0 software. The investigation focused on 15 key in-depth reports on machinery space incidences which were uploaded into the software. The results indicate that leakages on hot surfaces were the major causes of fire hazards in seafaring vessels. The results from using this methodology also highlighted two more fire hazards that were not so apparent in previous studies. They are generator fire and compressors fire. The results supported other studies about leakages on hot surfaces as a major contributor, but also clearly show that there are other hazardous factors of fire in machinery spaces that require further investigation

Solving large scale Max Cut problems via tabu search

In recent years many algorithms have been proposed in the literature for solving the Max-Cut problem. In this paper we report on the application of a new Tabu Search algorithm to large scale Max-cut test problems. Our method provides best known solutions for many well-known test problems of size up to 10,000 variables, although it is designed for the general unconstrained quadratic binary program (UBQP), and is not specialized in any way for the Max-Cut problem

From limit cycles to strange attractors

We define a quantitative notion of shear for limit cycles of flows. We prove that strange attractors and SRB measures emerge when systems exhibiting limit cycles with sufficient shear are subjected to periodic pulsatile drives. The strange attractors possess a number of precisely-defined dynamical properties that together imply chaos that is both sustained in time and physically observable.Comment: 27 page

Production and in vitro evaluation of macroporous, cell-encapsulating alginate fibres for nerve repair

The prospects for successful peripheral nerve repair using fibre guides are considered to be enhanced by the use of a scaffold material, which promotes attachment and proliferation of glial cells and axonal regeneration. Macroporous alginate fibres were produced by extraction of gelatin particle porogens from wet spun fibres produced using a suspension of gelatin particles in 1.5% w/v alginate solution. Gelatin loading of the starting suspension of 40.0, 57.0, and 62.5% w/w resulted in gelatin loading of the dried alginate fibres of 16, 21, and 24% w/w respectively. Between 45 and 60% of the gelatin content of hydrated fibres was released in 1 h in distilled water at 37 °C, leading to rapid formation of a macroporous structure. Confocal laser scanning microscopy (CLSM) and image processing provided qualitative and quantitative analysis of mean equivalent macropore diameter (48–69 μm), pore size distribution, estimates of maximum porosity (14.6%) and pore connectivity. CLSM also revealed that gelatin residues lined the macropore cavities and infiltrated into the body of the alginate scaffolds, thus, providing cell adhesion molecules, which are potentially advantageous for promoting growth of glial cells and axonal extension. Macroporous alginate fibres encapsulating nerve cells [primary rat dorsal root ganglia (DRGs)] were produced by wet spinning alginate solution containing dispersed gelatin particles and DRGs. Marked outgrowth was evident over a distance of 150 μm at day 11 in cell culture, indicating that pores and channels created within the alginate hydrogel were providing a favourable environment for neurite development. These findings indicate that macroporous alginate fibres encapsulating nerve cells may provide the basis of a useful strategy for nerve repair

On Bures fidelity of displaced squeezed thermal states

Fidelity plays a key role in quantum information and communication theory. Fidelity can be interpreted as the probability that a decoded message possesses the same information content as the message prior to coding and transmission. In this paper, we give a formula of Bures fidelity for displaced squeezed thermal states directly by the displacement and squeezing parameters and birefly discuss how the results can apply to quantum information theory.Comment: 10 pages with RevTex require

Comparing the reliability of networks by spectral analysis

We provide a method for the ranking of the reliability of two networks with the same connectance. Our method is based on the Cheeger constant linking the topological property of a network with its spectrum. We first analyze a set of twisted rings with the same connectance and degree distribution, and obtain the ranking of their reliability using their eigenvalue gaps. The results are generalized to general networks using the method of rewiring. The success of our ranking method is verified numerically for the IEEE57, the Erd\H{o}s-R\'enyi, and the Small-World networks.Comment: 7 pages, 3 figure